Pressure sensor module and electronic component

ABSTRACT

A pressure sensor module includes a pressure sensor, a bump, and a laminated substrate. The pressure sensor includes a semiconductor substrate; a cavity; a pressure-sensitive element; and a conductive section. The cavity is disposed inside the semiconductor substrate such that a thin-plate region of the semiconductor substrate is provided and the thin-plate region being defined as a diaphragm. The pressure-sensitive element is arranged at the diaphragm. The conductive section is electrically connected to the pressure-sensitive element and disposed on the face of the semiconductor substrate at a region excluding the diaphragm. The bump is electrically connected to the conductive section. The laminated substrate includes a wiring base material electrically connected to the pressure sensor via the bump. The wiring base material is disposed inside the laminated substrate. A face of the wiring base material is electrically connected to the bump and has an exposed area from the laminated substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pressure sensor module, and moreparticularly relates to a module structure that detects pressure in adiaphragm and has low fluctuation of pressure sensor characteristics,and a structure that can package the pressure sensor and applicationspecific integrated circuit (ASIC) or another semiconductor device athigh density and in a small size.

The present invention claims priority on Japanese Patent Application No.2008-114262, filed on Apr. 24, 2008, and the contents of which areincorporated herein by reference.

2. Description of the Related Art

Pressure sensors are used in various fields such as household electricappliances, medical equipment, and vehicle parts. Semiconductor pressuresensors are increasingly being used, since they are small and highlyreliable. Recently, with the aim of mounting pressure sensors inportable devices, there is a particular demand for a smaller packagestructure.

To realize a very small package, as disclosed in Japanese UnexaminedPatent Application, First Publication No. 2007-248212, the applicantconsidered a surface mountable chip size package (CSP), and proposed asmall pressure sensor module that can be realized by mounting a pressuresensor on a laminated substrate which an ASIC internally containingamplification and compensation circuits is buried in. FIG. 10 is arepresentative example of that structure. A pressure sensor 112including a diaphragm 111 is mounted on a laminated substrate 115 inwhich an ASIC 114 is buried in via a bump 113. While this structure issuitable for realizing a small module in which a combination of devicessuch as the ASIC 114 and the pressure sensor 112 are mounted, someproblems were discovered during subsequent systematic consideration.

In the conventional module structure shown in FIG. 10, since thepressure sensor 112 is mounted on a topmost face 115A of the laminatedsubstrate 115, stress generated in the laminated substrate 115 is liableto be applied to the pressure sensor 112. Therefore, due to the stressapplied from the laminated substrate 115 to the pressure sensor 112,there is some fluctuation in the output characteristics of the pressuresensor 112 before and after mounting it on the laminated substrate 115.This makes it difficult to obtain a pressure sensor module 130 havingdesired output characteristics.

SUMMARY OF THE INVENTION

The present invention has been realized in view of the above problems,and aims to provide a pressure sensor module in which fluctuation in theoutput characteristics of a pressure sensor due to stress generated inthe laminated substrate is unlikely to occur, enabling the pressuresensor to achieve desired output characteristics.

A pressure sensor module according to a first aspect of the presentinvention includes a pressure sensor including: a semiconductorsubstrate; a cavity (space); a pressure-sensitive element; and aconductive section, wherein the cavity is disposed inside thesemiconductor substrate and arranged substantially along a face of thesemiconductor substrate at a substantially central area of the face suchthat a thin-plate region of the semiconductor substrate is provided atone side of the cavity, the thin-plate region being defined as adiaphragm, wherein the pressure-sensitive element is arranged at thediaphragm, wherein the conductive section is electrically connected tothe pressure-sensitive element and is disposed on the face of thesemiconductor substrate at a region excluding the diaphragm; a bumpelectrically connected to the conductive section; and a laminatedsubstrate including a wiring base material electrically connected to thepressure sensor via the bump, wherein the wiring base material isdisposed inside the laminated substrate, and a face of the wiring basematerial is electrically connected to the bump and has an exposed areafrom the laminated substrate.

A pressure sensor module according to a second aspect of the presentinvention is characterized in that, in the first aspect, the pressuresensor is surrounded by the laminated substrate such that at least aface of the semiconductor substrate is exposed.

A pressure sensor module according to a third aspect of the presentinvention is characterized in that, in the first aspect, the wiring basematerial is a semiconductor device.

An electronic component according to a fourth aspect of the presentinvention is characterized in that it includes the pressure sensormodule of the first aspect.

According to the present invention, the wiring base material that iselectrically connected to the pressure sensor is arranged within thelaminated substrate, and the pressure sensor is mounted thereon. Whilestress generated in the laminated substrate is greatest at a topmostface of the laminated substrate, in this invention the wiring basematerial is arranged within the laminated substrate. Therefore, thestress applied to the pressure sensor can be reduced more than when itis mounted on a conventional pressure sensor module. Since this makes itpossible to suppress the fluctuation in output characteristics of thepressure sensor before and after mounting due to the stress, and toprovide a pressure sensor module with desired output characteristics.

The above and other aspects of the present invention will becomeapparent upon consideration of the following detailed descriptions ofexemplary embodiments thereof, particularly when taken in conjunctionwith the accompanying drawings wherein like reference numerals in thevarious figures are utilized to designate like components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing one example of apressure sensor module according to a first embodiment of the presentinvention.

FIG. 2 is an electrical wiring view showing one example of apressure-sensitive element.

FIG. 3 is a schematic cross-sectional view showing one example of apressure sensor module according to a second embodiment of the presentinvention.

FIG. 4 is a schematic cross-sectional view showing one example of apressure sensor module according to a third embodiment of the presentinvention.

FIG. 5 is a schematic cross-sectional view showing one example of apressure sensor module according to a fourth embodiment of the presentinvention.

FIG. 6 is a schematic cross-sectional view showing one example of apressure sensor module according to a fifth embodiment of the presentinvention.

FIG. 7 is a schematic cross-sectional view showing one example of apressure sensor module according to a sixth embodiment of the presentinvention.

FIG. 8 is a schematic cross-sectional view showing one example of apressure sensor module according to a seventh embodiment of the presentinvention.

FIG. 9 is a schematic cross-sectional view showing one example of apressure sensor module according to a eighth embodiment of the presentinvention.

FIG. 10 is a schematic cross-sectional view showing a conventionalpressure sensor module.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention will be explained in detail with referenceto the drawings, these are not to be considered limitative of theinvention, which can be modified in various ways without departing fromits main features.

First Embodiment

FIG. 1 is a schematic cross-sectional view showing one example of apressure sensor module according to a first embodiment of the presentinvention. In the embodiment, a pressure sensor module 30A mainlyincludes a pressure sensor 10, bumps 18, and a laminated substrate 20.In a face 11 a of a semiconductor substrate 11, the pressure sensor 10includes a cavity (gap portion) 13 that extends substantially parallelto the face 11 a inside a central area “α” of the semiconductorsubstrate 11. A thin-plate region at a side 13 a of the cavity 13 isdefined as a diaphragm 14. Pressure-sensitive elements 15 are arrangedin the diaphragm 14. The pressure sensor 11 includes conductive sections16 that are electrically connected to the pressure-sensitive elements15, wherein the conductive sections 16 are arranged in a regionexcluding the diaphragm 14 on the face 11 a. The bump 18 is arranged ineach conductive section 16 respectively, and is electrically connectedto the conductive section 16 separately. The laminated substrate 20includes a wiring base material 21 that is electrically connected to thepressure sensor 10 via the bumps 18. Further, the wiring base material21 is arranged inside the laminated substrate 20. At least one part of aface 21 a of the wiring base material 21 that is electrically connectedto the bumps 18 is exposed from the laminated substrate 20. Each ofthese constituent parts will be explained in detail below.

The semiconductor substrate 11 can be made from, for example, a siliconwafer or such like. In this embodiment, the face 11 a of thesemiconductor substrate 11 where the diaphragm 14 is formed is arrangedopposite the face 21 a of the wiring base material 21.

The cavity 13 is a space formed inside the semiconductor substrate 11and adjacent to the face 11 a of the semiconductor substrate 11. In thisembodiment, the cavity 13 is an airtight space in the semiconductorsubstrate 11 to which a face of the diaphragm 14 faces. The size of thecavity 13 can be set appropriately such that the diaphragm 14 has adesired thickness.

There are no limitations on the shape of the diaphragm 14, which needonly obtain a direct proportional relationship between pressure andstatic capacitance within the load pressure range of the measuredtarget, and can be any shape such as rectangular, square, circular; inthis example it is rectangular.

The pressure-sensitive elements 15 are gauge resistances (R1 to R4)arranged in a peripheral portion of the diaphragm 14, their outputsignals varying in accordance with the amount of bending of thediaphragm 14, and pressure thereby being detected. FIG. 2 is anelectrical wiring view showing the pressure-sensitive elements 15.

As shown in FIG. 2, these gauge resistances (R1 to R4) are electricallyconnected by lead wires (not shown) to form a Wheatstone bridge. Sinceforces of compression and elongation in the peripheral portion of thediaphragm 14 are easily applied to the pressure-sensitive elements 15, ahighly sensitive pressure sensor 10 can be obtained.

In this embodiment, the pressure-sensitive elements 15 is arranged nearthe diaphragm 14 and buried in the semiconductor substrate 11 at theface 11 a. Alternatively, they can be arranged at any location thatenables them to detect bending of the diaphragm 14, e.g. they canprotrude from the face 11 a of the semiconductor substrate 11.

The conductive sections 16 are made by fabricating a thin film of anytype of metal that is generally used as material for electrode, such asAl, Cr, Au, Ag, Cu, and Ti, on the face 11 a of the semiconductorsubstrate 11 using a method such as vaporization, sputtering,non-electrolytic plating, etc.

The pattern of the conducive sections 16 can be patterned by using amask to cover portions of the face 11 a of the semiconductor substrate11 where the conductive sections will not be fabricated and forming ametal film only in portions where the conductive sections will befabricated, or by forming a uniform metal film on the face 11 a of thesemiconductor substrate 11 and then performing photolithography to etchthis metal film to a desired pattern.

There are no particular limitations on the bumps 18, which need only becapable of electrically connecting the pressure sensor 10 to the wiringbase material 21 arranged in the laminated substrate 20. When thepressure sensor 10 and the laminated substrate 20 are electricallyconnected via the bumps 18, a gap (interval) 1 is formed between theface 21 a of the wiring base material 21 and the face 11 a of thesemiconductor substrate 11. Due to the formation of the gap 1, thepressure sensor 10 is not directly subjected to stress from thelaminated substrate 20, enabling that stress to be alleviated.

The laminated substrate 20 is configured by superimposing, for example,three substrates 20 a, 20 b, and 20 c, as shown in FIG. 1. In thisembodiment, the laminated substrate 20 need only have two or moresubstrates composed of the same or different materials, there being noparticular limitation on the number of substrates that are superimposed.In this embodiment, three substrates are superimposed. Alternatively,two substrates are acceptable, as is a laminated substrate formed bysuperimposing a plurality of substrates.

There are no particular limitations on the substrates that constitutethe laminated substrate 20, and conventional substrates can be used,such as a flexible printed circuit board with a polyimide base, etc.

A wiring base material 21 is arranged on the laminated substrate 20, andis electrically connected to the pressure sensor 10. A wiring portion 23is also arranged on the laminated substrate 20, and is electricallyconnected to the wiring base material 21.

The wiring portion 23 connects a pressure signal from the pressuresensor 10 outputted from the conductive sections 16 or the wiring basematerial 21 to, for example, an amplification circuit or a temperaturecompensation circuit fabricated on the laminated substrate 20. There areno particular limitations on the wiring portion 23, which can be madefrom a metal that is generally used as material for electrode, such asAl, Cl, Au, Ag, Cu, and Ti.

The wiring base material 21 is arranged on the laminated substrate 20and the pressure sensor 10 is mounted on it.

By arranging the wiring base material 21 within the laminated substrate20, and mounting the pressure sensor 10 so that the diaphragm 14 isopposite the wiring base material 21, mechanical stress from the outsidecan be prevented from acting on and damaging sections that arevulnerable to damage, such as the joined portions between the diaphragm14 and the bumps 18.

Conductors 22 are arranged on the wiring base material 21, andelectrically connect to the conductive sections 16 of the pressuresensor 10. There are no particular limitations on the conductors 22,which can be made from any metal that is generally used as material forelectrode, such as Al, Cr, Au, Ag, Cu, and Ti, this metal being selectedwith due consideration for its compatibility with the wiring basematerial 21 and the bumps 18.

According to this embodiment, the wiring base material 21 that iselectrically connected to the pressure sensor 10 is arranged within thelaminated substrate 20, and the pressure sensor 10 is mounted thereon.Since stress generated in the laminated substrate 20 is greatest at thetopmost face 20A of the laminated substrate 20, the stress applied tothe pressure sensor 10 can be reduced more than when it is mounted on aconventional pressure sensor module.

Also, rather than mounting the pressure sensor 10 directly on thelaminated substrate 20, it is arranged at an gap from side faces of thelaminated substrate 20 and the face 21 a of the laminated substrate 20.Stress generated in the laminated substrate 20 and applied to thepressure sensor 10 is thus alleviated, and fluctuation in outputcharacteristics of the pressure sensor 10 before and after mountingcaused by this stress can be suppressed, whereby a pressure sensormodule 30A with desired output characteristics can be provided.

In particular, this invention can be configured simply by arranging thewiring base material 21 within a conventional laminated substrate, andmounting the pressure sensor 10 on the wiring base material 21. Thismakes it easy to provide a pressure sensor module 30A which is unlikelyto have fluctuating output characteristics.

Since the wiring base material 21 is arranged within the laminatedsubstrate 20, the pressure sensor module 30A which the pressure sensor10 is mounted in can be made thinner, and mechanical stress from theoutside can be prevented from acting on and damaging sections that arevulnerable to damage, such as the joined portions between the diaphragm14 and the bumps 18.

Second Embodiment

FIG. 3 is a schematic cross-sectional view showing one example of apressure sensor module 30B according to a second embodiment of thepresent invention. Like parts to those in the first embodiment aredesignated with like reference codes, and are not repetitiouslyexplained.

In this embodiment, in the face that the pressure sensor 10 is mountedon, the topmost face 20A of the laminated substrate 20 is at the sameposition as the top face of the pressure sensor 10 (other face 11 b ofthe semiconductor substrate 11) or higher than that. Consequently, sidefaces 11 c of the semiconductor substrate 11 are enclosed by thelaminated substrate 20 a, and, in the completed pressure sensor module30B, direct outside force against the pressure sensor 10 is considerablysuppressed.

Therefore, in addition to the effects of the first embodiment describedabove, direct outside force against the pressure sensor 10 can beconsiderably suppressed both during delivery and after mounting it on aproduct, and dramatic reductions can be achieved in stress appliedduring delivery affects the diaphragm 14, change in the outputcharacteristics of the pressure sensor 10, detachment of the pressuresensor 10 from the laminated substrate 20 after being mounting on theproduct, or problems arising from breakage in electrical connection anddamage to the diaphragm 14.

Third Embodiment

FIG. 4 is a schematic cross-sectional view showing one example of apressure sensor module 30C according to a third embodiment of thepresent invention. In this embodiment, the pressure sensor module 30Cdiffers from the pressure sensor module 30A of the first embodiment inthat a semiconductor device 31 is arranged within the laminatedsubstrate 20, and electrically connected to the pressure sensor 10. Likeparts to those in the first embodiment are designated with likereference codes, and are not repetitiously explained.

There are no particular limitations on the semiconductor device 31,which can include, for example, an application specific integratedcircuit (ASIC) that performs sensitive amplification, temperaturecompensation, etc. for the pressure sensor 10.

According to the pressure sensor module 30C of the third embodiment, thesemiconductor device (e.g. ASIC) 31 that controls the pressure sensor 10is provided within the laminated substrate 20, thereby eliminating theneed for an external control circuit or such like to control thepressure sensor 10. Therefore, in addition to the effects obtained bythe first embodiment, this embodiment can provide the pressure sensor 10and a semiconductor device 31 such as a control circuit for the pressuresensor 10 together in one package. Thereby the pressure sensor module30C that is small and thin can be obtained. Moreover, by burying avariety of semiconductor devices 31 in the laminated substrate 20, ahighly functional, high-density pressure sensor package can be provided.

In this embodiment, as in the second embodiment, the topmost face 20A ofthe laminated substrate 20 can be exposed so that it is at the sameposition as the other face 11 b of the semiconductor substrate 11, orhigher than that, the pressure sensor 10 being covered with (surroundedby) the laminated substrate 20. This obtains the same effects as thoseof the second embodiment.

Fourth Embodiment

FIG. 5 is a schematic cross-sectional view showing one example of apressure sensor module 30D according to a fourth embodiment of thepresent invention. In this invention, the pressure sensor module 30Ddiffers from the pressure sensor module 30A of the first embodiment inthat a semiconductor device 31 is used as a wiring base material 21arranged within the laminated substrate 20.

In the semiconductor device 31, an electrical circuit 32 is formed on aface 31 a where the pressure sensor 10 is mounted, a portion of thiscircuit 32 is electrically connected to the bumps 18, and thesemiconductor device 31 is electrically connected to the pressure sensor10. This enables signals to be exchanged between the pressure sensor 10and the semiconductor device 31.

In this embodiment, by using the semiconductor device 31 as the wiringbase material 21, in addition to the effects of the first and the thirdembodiments mentioned above, a pressure sensor module 30D that issmaller and thinner than the pressure sensor module 30C of the thirdembodiment can be obtained.

In this embodiment, as in the second embodiment, the topmost face 20A ofthe laminated substrate 20 can be exposed so that it is at the sameposition as the other face 11 b of the semiconductor substrate 11, orhigher than that, the pressure sensor 10 being covered with thelaminated substrate 20. The same effects as those of the secondembodiment can be obtained.

Fifth Embodiment

FIG. 6 is a schematic cross-sectional view showing one example of apressure sensor module 30E according to a fifth embodiment of thepresent invention.

In this embodiment, the pressure sensor module 30E mainly includes apressure sensor 60, bumps 18, and a laminated substrate 20. In a face 61a of a semiconductor substrate 61, the pressure sensor 60 includes acavity 63 that extends substantially parallel to the face 61 a inside acentral area “α” of the semiconductor substrate 61. A thin-plate regionat a side of the cavity 63 is defined as a diaphragm 64.Pressure-sensitive elements 65 are arranged in the diaphragm 64. Thepressure sensor 60 also includes conductive sections 66 that areelectrically connected to the pressure-sensitive elements 65 and arearranged in a region excluding the diaphragm 64 on the face 61 a. Thebump 18 is arranged in each conductive section 66 respectively, and iselectrically connected to the conductive sections 66 separately. Thelaminated substrate 20 includes a wiring base material 21 that iselectrically connected to the pressure sensor 60 via the bumps 18.

Further, the wiring base material 21 is arranged inside the laminatedsubstrate 20, and at least one part of a face 21 a of the wiring basematerial 21 that is electrically connected to the bumps 18 is exposedfrom the laminated substrate 20.

In this embodiment, the pressure sensor module 30E differs from thepressure sensor module 30A of the first embodiment in regard to threepoints, firstly, that through-hole electrodes 62 are provided in thepressure sensor 60, so that one end 62 a of the through-hole electrode62 is electrically connected to the conductive section 66 and anotherend 62 b of the through-hole electrode 62 is exposed on other face 61 bof the semiconductor substrate 61, secondly, that the through-holeelectrodes 62 are electrically connected to the wiring base material 21via the bumps 18, and thirdly, that the diaphragm 64 is arranged on theface 61 a on the reverse of the semiconductor substrate 61 with respectto the face 61 b opposite the laminated substrate 20.

The semiconductor substrate 61, the cavity 63, the diaphragm 64, thepressure-sensitive elements 65, and the conductive sections 66 arerespectively similar to the semiconductor substrate 11, the cavity 13,the diaphragm 14, the pressure-sensitive elements 15, and the conductivesections 16 of the first embodiment.

There are no particular limitations on the through-hole electrodes 62,conventional electrodes can be used; and which can be formed by, forexample, a through-hole in the semiconductor substrate 61 can be filledwith gold, another metal material, or a solder alloy, etc.

According to this embodiment, the wiring base material 21 that iselectrically connected to the pressure sensor 60 is arranged in thelaminated substrate 20 and the pressure sensor 60 is mounted on it.Since stress generated in the laminated substrate 20 is greatest at thetopmost face 20A of the laminated substrate 20, the stress applied tothe pressure sensor 60 can be reduced more than when it is mounted on aconventional pressure sensor module. Also, rather than mounting thepressure sensor 60 directly on the laminated substrate 20, it isarranged at an gap from side faces of the laminated substrate 20 and theface 21 a of the laminated substrate 20.

The fluctuation in output characteristics of the pressure sensor 60before and after mounting caused by the stress can be suppressed,whereby a pressure sensor module 30E with desired output characteristicscan be provided.

In particular, this invention can be configured simply by arranging thewiring base material 21 within a conventional laminated substrate, andmounting the pressure sensor 60 on the wiring base material 21. Thismakes it easy to provide a pressure sensor module 30E whose outputcharacteristics are unlikely to fluctuate.

Since the wiring base material 21 is arranged within the laminatedsubstrate 20, the pressure sensor module 30E which the pressure sensor60 is mounted on can be made thinner, and mechanical stress from theoutside can be prevented from acting on and damaging sections that arevulnerable to damage, such as the joined portions between the diaphragm14 and the bumps 18.

Sixth Embodiment

FIG. 7 is a schematic cross-sectional view showing one example of apressure sensor module 30F according to a sixth embodiment of thepresent invention. Like parts to those in the first and fifthembodiments are designated with like reference codes, and are notrepetitiously explained.

In this embodiment, at the face that the pressure sensor 60 is mountedon, the topmost face 20A of the laminated substrate 20 is at the sameposition as the top face of the pressure sensor 60 (a face 61 a of thesemiconductor substrate 61) or higher than that. Side faces 61 c of thesemiconductor substrate 61 are thus enclosed by the laminated substrate20 a, and, in the completed pressure sensor module 30F, direct outsideforce applied to the pressure sensor 60 is considerably suppressed.

Therefore, in addition to the effects of the fifth embodiment describedabove, direct outside force against the pressure sensor 60 can beconsiderably suppressed both during delivery and after mounting it on aproduct, and dramatic reductions can be achieved in the effects ofstress applied during delivery on the diaphragm 64 and leading to changein the output characteristics of the pressure sensor 60, detachment ofthe pressure sensor 60 from the laminated substrate 20 after beingmounting on the product, or problems arising from breakage in electricalconnection and damage to the diaphragm 64.

Seventh Embodiment

FIG. 8 is a schematic cross-sectional view showing one example of apressure sensor module 30G according to a seventh embodiment of thepresent invention. In this embodiment, the pressure sensor module 30Gdiffers from the pressure sensor module 30E of the fifth embodiment inthat a semiconductor device 31 is additionally arranged within thelaminated substrate 20.

There are no particular limitations on the semiconductor device 31,which can include, for example, an application specific integratedcircuit (ASIC) for performing sensitive amplification, temperaturecompensation, etc., for pressure, sensor 60.

According to the pressure sensor module 30G of this embodiment, as inthe pressure sensor module 30B of the second embodiment, thesemiconductor device (e.g. ASIC) 31 for controlling the pressure sensor60 is provided within the laminated substrate 20, thereby eliminatingthe need for an external control circuit or such like to control thepressure sensor 60.

Therefore, in addition to the effects obtained in the fifth embodiment,this embodiment can provide the pressure sensor 60 and the semiconductordevice 31 such as a control circuit for the pressure sensor 60 togetherin one package, and thereby the pressure sensor module 30G that is smalland thin can be obtained. Moreover, by burying various semiconductordevices 31 in the laminated substrate 20, a highly functional,high-density pressure sensor package can be provided.

Incidentally, in this embodiment, as in the sixth embodiment, thetopmost face 20A of the laminated substrate 20 can be exposed so that itis at the same position as the face 61 a of the semiconductor substrate61, or higher than that, the pressure sensor 60 being covered with thelaminated substrate 20. The same effects as those of the sixthembodiment can be obtained.

Eighth Embodiment

FIG. 9 is a schematic cross-sectional view showing one example of apressure sensor module 30H according to an eighth embodiment of thepresent invention. In this embodiment, the pressure sensor module 30Hdiffers from the pressure sensor module 30E of the fifth embodiment inthat a semiconductor device 31 is used as a wiring base material 21arranged within the laminated substrate 20.

In the semiconductor device 31, an electrical circuit 32 is formed on aface 31 a where the pressure sensor 60 is mounted, a portion of thiscircuit 32 is electrically connected to the bumps 18, and thesemiconductor device 31 is electrically connected to the pressure sensor60. Signals can thus be exchanged between the pressure sensor 60 and thesemiconductor device 31.

In this embodiment, by using the semiconductor device 31 as the wiringbase material 21, in addition to the effects of the fifth and seventhembodiments mentioned above, it is possible to obtain a pressure sensormodule 30H that is smaller and thinner than the pressure sensor module30G of the seventh embodiment.

In this embodiment, as in the sixth embodiment, the topmost face 20A ofthe laminated substrate 20 can be exposed 30 that it is at the sameposition as the face 61 a of the semiconductor substrate 61, or higherthan that, the pressure sensor 60 being covered with the laminatedsubstrate 20. The same effects as the sixth embodiment cm be obtained.

In the pressure sensor module 30 according to the first to the eighthembodiments described above, the coefficients of thermal expansion (CTE)of the wiring base material 21 is preferably approximately the same asthat of the semiconductor substrates 11 and 61 of the pressure sensors10 and 60.

When a pressure sensor is attached by direct reflow on a laminatedsubstrate in the conventional manner at a certain temperature (usuallyaround 260° C.), due to the difference of the CTE between the sensor andthe substrate, at the usage temperature of the pressure sensor (e.g.room temperature), there is residual stress near the soldered bump.Consequently, stress on the diaphragm changes before and after mountingthe pressure sensor, whose output characteristics change as a result.

Due to the difference of CTE between the pressure sensor and thelaminated substrate, residual stress changes (creep) over time, wherebythe characteristics of the sensor also fluctuate over time. When thermalfluctuation is added to this, the sensor and the substrate expand andcontract in accordance with their CTE, resulting in poor thermalreliability.

If the CTE of the wiring base material 21 is approximately the same asthat of the semiconductor substrates 11 and 61 of the pressure sensors10 and 60, stress caused by difference in their CTE can be suppressed.It is also possible to minimize residual stress after the pressuresensors 10 and 60 are attached by direct reflow to the laminatedsubstrate 20, and fluctuation (creep) in this stress over time.

This makes it possible to reduce fluctuation in the outputcharacteristics of the pressure sensors 10 and 60 before and aftermounting, to maintain desired output characteristics, and todramatically increase reliability of the temperature cycle and the like.

The wiring base material 21 can be modified as appropriate in accordancewith the semiconductor substrates 11 and 61 used in the pressure sensors10 and 60. For example, it can be made from silicon, ceramic, glass,etc.

Incidentally, when using the semiconductor device 31 as the wiring basematerial 21, the CTE of the wiring base material 21 is preferablyapproximately the same as that of the semiconductor substrates 11 and 61of the pressure sensors 10 and 60. As with the wiring base material 21described earlier, this makes it possible to suppress stress caused bydifference in the CTE, and to minimize residual stress after thepressure sensors 10 and 60 are attached by direct reflow on thelaminated substrate 20 and fluctuation (creep) in this stress over time.

This makes it possible to obtain a pressure sensor module which canreduce fluctuation in the output characteristics of the pressure sensors10 and 60 before and after mounting, can maintain desired outputcharacteristics, and can dramatically increase the reliability of thetemperature cycle and the like.

The semiconductor device 31 can be modified as appropriate in accordancewith the semiconductor substrates 11 and 61 used in the pressure sensors10 and 60. For example, it can be made from silicon, ceramic, glass,etc.

An electronic component of the present invention includes the pressuresensor module 30 described in any one of the first to the eighthembodiments described above. Therefore, since the electronic componentis hardly affected by stress from the outside or inside, it becomespossible to provide an electronic component that can detect pressurewith high precision and superior reproducibility.

Since the invention can provide a pressure sensor module that alleviatesstress applied to a pressure sensor and maintains desired outputcharacteristics, it is ideally applicable to various electroniccomponents which are used, for example, in measuring pressure such asair pressure, water pressure, and oil pressure, and which can measurewith high precision and superior reproducibility.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto the exemplary embodiments. It will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the scope of the invention as defined bythe following claims.

1. A pressure sensor module comprising: a pressure senior; the pressuresensor comprising: a semiconductor substrate; a cavity; apressure-sensitive element; and a conductive section, wherein the cavityis disposed inside the semiconductor substrate and arrangedsubstantially along a face of the semiconductor substrate at asubstantially central area of the face such that a thin-plate region ofthe semiconductor substrate is provided at one side of the cavity, thethin-plate region being defined as a diaphragm, wherein thepressure-sensitive element is arranged at the diaphragm, wherein theconductive section is electrically connected to the pressure-sensitiveelement and is disposed on the face of the semiconductor substrate at aregion excluding the diaphragm; a bump electrically connected to theconductive section; and a laminated substrate including a wiring basematerial electrically connected to the pressure sensor via the bump,wherein the wiring base material is disposed inside the laminatedsubstrate, and a face of the wiring base material is electricallyconnected to the bump and has an exposed area from the laminatedsubstrate.
 2. The pressure sensor module according to claim 1, whereinthe pressure sensor is surrounded by the laminated substrate such thatat least a face of the semiconductor substrate is exposed.
 3. Thepressure sensor module according to claim 1, wherein the wiring basematerial is a semiconductor device.
 4. An electronic componentcomprising the pressure sensor module according to claim 1.